/Engine/Source/Runtime/Engine/Classes/PhysicsEngine/ConstraintInstance.h
Set the constraint transform components specified by the SnapFlags to their default values (derived from the parent and child bone transforms).
void SnapTransformsToDefault ( const EConstraintTransformComponentFlags SnapFlags, const [UPhysicsAsset](API\Runtime\Engine\PhysicsEngine\UPhysicsAsset) *const PhysicsAsset )